Effect of crural myotomy on the incidence and mechanism of gastroesophageal reflux in cats

Abstract

Background: Esophagogastric junction (EGJ) pressure is the major barrier to gastroesophageal reflux. Recent studies suggest that contraction of the crural diaphragm increases esophagogastric junction pressure. Whether this increase in EGJ pressure is important in the prevention of gastroesophageal reflux is not known. Our aim in this study was to determine the effects of crural myotomy on the occurrence of gastroesophageal reflux. Methods: The spontaneous and stress gastroesophageal reflux before and after a surgical crural myotomy in four cats was studied. Spontaneous gastroesophageal reflux was recorded in the awake cats through a pH probe, placed via an esophagostomy, for periods of 12–24 hours. Stress reflux was studied during periods of airway obstruction and abdominal compression in anesthetized animals using the technique of simultaneous esophageal manometry and pH monitoring. Results: There was a significant increase in the frequency of spontaneous acid reflux after crural myotomy. In anesthetized animals, there was an increase in the EGJ pressure during airway obstruction, which was abolished by a crural myotomy. Abdominal compression caused a reflex contraction at the EGJ that was not affected by crural myotomy. The crural myotomy resulted in a significant increase in the frequency of acid reflux during airway obstruction but not during abdominal compression. Conclusions: It is concluded that the crural diaphragm is important in the prevention of gastroesophageal reflux and its dysfunction leads to an increased incidence of gastroesophageal reflux.